Place all ingredients in a blender; process until smooth.
Protein and monounsaturated fat from the peanut butter, potassium from the banana, and protein and calcium from the yogurt will get your day off to a great start. Peel and slice bananas to freeze individually in zip-top bags for smoothies and shakes.
My husband I and both loved this smoothie and had it for bfast two days in a row. I'm buying extra banana this week just to freeze some to have on hand to make the smoothie again. I forgot the chocolate syrup the first time and thought it tasted fine; the 2nd time I added the syrup and couldn't really tell the difference. I'll probably leave the chocolate syrup out in the future to save the calories, and I may try plain nonfat yogurt instead of flavored vanilla. We drank the smoothie with some breakfast bread from the bakery. Yum!